Hydrocarbon conversion



Sept. 29, 1953 M. o. KILPATRICK 2,653,903

HYDROCARBON CONVERSION Filed June 9, 1950 FLUE GA v 2| f; a H- j fi g /l9 PEBBLE I HEATING FUEL GAS-AIR CHAMBER Y HOT 22 GASEOUS CRACKING I4 PRODUCT) I m I I 24- O E Io I 3 METHANE, HYDROGEN I L1 NORMALLY I2/ 29 Low BOILING GASEOUS OLEFINS HYDROCARBON 23 LIGHT- FEED HYDROCARBON Low BOILING cRAcKINc PARAFFINs R OT LIGHT T AL GAS OIL 36 t CRACKING EFFLUENT (I) I6 v RESIDUUM 27 CRACKING i l FEED 25 28 34 a lo CARBON- 3 1 ACEOUS w I3 I MATERIAL 4 37 CRR'C KIG I I v HYDROCARBON CHAMBER uNREAIcTEo IN CHAMBER I2 mvmrox. l8 M. O.KILPATRICK BY 2 q A TTORNE VS Patented Sept. 29, 1953 HYDROCARBON CONVERSION Myron 0. Kilpatrick, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware Application June 9, 1950, Serial No. 167,139

7 9 Claims. 1

This invention relates to the conversion of hydrocarbons. In one embodiment this invention relates to a combination conversion process for reacting low-boiling hydrocarbons and higher boiling hydrocarbons in a single conversion system. In another embodiment this invention relates to a combination process for crackingnormally gaseous hydrocarbons and oil residuum stocks.

Hydrocarbon oil residuum stocks are by-product heavy residual or bottoms fractions obtained from distillation of crude petroleum, or resulting from certain refining operations. When further treatment of these stocks is attempted such as distillation or cracking, or the like, excessive decomposition of the heavy material to carbon or carbon-rich materials generally occurs, resulting in the rapid accumulation of carbonaceous deposits in the treating system and necessitating shut-down of equipment after short operating periods. Such short operating periods are uneconomical from the standpoint not only of the cost of shutting down and subsequently starting up, but also with respect to the time and manpower requirements for removing the carbonaceous deposits and for readying the equipment for start-up.

' Various processes have been proposed in the art for the thermal conversion, or cracking, of light hydrocarbons, particularly normally gaseous hydrocarbons. Such a conversion reaction is highly endothermic and requires a large input of heat at high temperature. Cracking effluent is withdrawn from the conversion zone and cooled prior to recovery of the desired products formed. Although this type of operation is suitable in many instances, the heat carried from the conversion system in the efiiuent is often inefficiently recovered.

The use of pebble heater apparatus has been proposed by many workers in the art as pro-. viding numerous advantages over other known means for cracking hydrocarbons, particularly for the reason that high cracking temperatures can be provided together with accurately controlled contact times to provide the desired cracking product in selectively high yield.

The term pebble, as used throughout the specification, denotes any solid refractory 'material of flowable form and size that can be utilized to carry heat from one zone to' another. Pebbles are preferably substantially spherical and are about a inch to 1 inch in diameter, the preferred range being about A; to /2 inch. Pebbles are formed of a refractory material which will withstand temperatures at least as high as the highest temperature obtained in the pebble heating chamber, and must be capable also of Withstanding temperature changes within the apparatus. Refractory materials, such as metal alloys, ceramics, and other satisfactory materials, can be utilized to form pebbles. Silicon carbide, alumina, periclase, thoria, beryllia, Stellite, zirconia, and mullite, may be satisfactorily used to form such pebbles or may be used in admixture with each other or with other materials. Pebbles formed of such materials, when properly fired, serve very well at high temperatures. some pebbles withstand temperatures up to about 3500 F. Pebbles which are used may be either inert or catalytic as used in any selected process.

A pebble heater system, or pebble heater apparatus, as it is often referred to, usually comprises a series of substantially vertically extending zones, often in vertical alignment with each other and connected by relatively narrow interconnecting zones or throats. Generally, the top or upper zone is employed as a pebble heating zone or chamber, and the succeeding lower zones as conversion zones, cooling zones, or the like, as required in the specific process. A combustion zone or chamber is often positioned adjacent or in close proximityto the sides of the lower portion of the pebble heating zone, and hot combustion gas formed in the combustion chamber is passed through the mass of pebbles in the pebble heating zone in heat exchange relation with the cooler pebbles therein. A hot gas source other than a combustion chamber is sometimes employed.

My process can be used to convert normally liquid hydrocarbons, i. e., pentanes and higher boiling hydrocarbons, preferably light gas oils and high boiling hydrocarbon materials such as heavy gas oils, fuel oils, crude residua, and the like. Production of aromatics and olefins, particularly ethylene, is high when ethane and/or propane are cracked in the first cracking zone, and a heavy gas oil, fuel oil, or crude residuum is converted in the second cracking zone in accordance with the process of my invention; these oils each having a boiling range preferably above 700 F.

With reference to the attached drawing,one embodiment of the process of my invention will be specifically disclosed. The figure is a diagrammatic illustration of one form of apparatus in which my process can be practiced. It is to be understood that this flow diagram is diagrammatic only and can be altered in many respects 3 by those skilled in the art, and yet remain within the scope of my invention.

Referring to the figure, a fluent mass of pebbles l substantially filling pebble heating chamber ll, light hydrocarbon cracking chamber l2, and oil cracking chamber I3, and interconnecting throats I4 and I6, is passed by gravity through these chambers and through pebble outlet conduit IT in the bottom of chamber I3, and through pebble flow control means, or star valve l8, to elevator l9. Elevator I9 transfers pebbles from valve I8 to pebble inlet conduit 2 I in the top of chamber I l, for recirculation through the pebble system. By regulation of valve It, a moving com tiguous column of pebbles is maintained throughout the apparatus from conduit 2| to star valve l 8.

A combustible fuel-oxygen mixture, such as a mixture of natural gas and air, is introduced into pebble heating chamber ll through line 22 and burned therein on the surfaces of pebbles in pebble mass I0. Suflicient free oxygen is present in the combustible gas mixture introduced through line 22 for the purpose of burning carbonaceous matter from the surfaces of pebbles reintroduced by elevating means l9, into chamber H, as described hereafter. Hot combustion gas formed from burning the combustible fuel mixture in chamber II is passed upwardly therethrough in countercurrent flow to, and heat exchange relation with pebbles, to heat them to a temperature above apredetermined cracking temperature required in cracking chamber 12. Generally, the cracking temperature in chamber [2 is within the limits of from 1300 to 2200 F., and the temperatureto which pebbles are heated in chamber II is generally from 100 to 300 F. above that cracking temperature.

A normally gaseous hydrocarbon to be cracked in chamber I2 is introduced thereinto at a point in a lower portion, through line 23. and contacted in countercurrent flow relation with pebbles in mass previously heated in chamber H. In this manner, hydrocarbon feed from line 23 is heated in chamber 12 to the requisite cracking temperature, and converted to cracking-product. Pebbles thus contacted with hydrocarbons in chamber l2 are cooled, as a result of the heat exchange, to a temperature generally from 200 to 800 F. below the temperature at which they are introduced into chamber [2. Hot gaseous cracking product is withdrawn from chamber l2 at a point in an upper portion thereof through line 24 and introduced into chamber I3 at a point in a lower portion thereof and contacted in countercurrent flow, and heat exchange relation with pebbles in mass l0, previously utilized in chamber I2 and. cooled as already described. Hydrocarbon oil cracking feed is introduced into chamber I3 through line 26. and contacted therein in concurrent flow relation with pebbles in mass [0. Operating, in this manner, heat carried from chamber 12 in the gaseous eflluent is utilized in cracking chamber [3 tov heat pebbles and oil therein, to a requisite temperature, to. crack the oil. Hot etlluent from chamber 12 is thereby quickly quenched. Furthermore, the partial pressure of oil vapors formed in chamber [3 is reduced by the presence of eflluent gases from chamber l2, and the amount of coke formation in chamber I3 is minimized, thus providing for an increase in the efficiency of the oil cracking reaction.

A contiguous mass of flowable particulate con-- tact material, or pebbles, fills the pebble heating zone and each of the succeeding zones together with the interconnecting zones or throats, and flows downwardly through these zones by gravity. Pebbles are discharged from the bottom of the lowermost zone of the series, at a controlled rate, and returned, usually by elevating means, into the upper portion of the pebble heating zone.

Pebble heater apparatus is generally employed in the thermal treatment or conversion of hydrocarbon materials. Operation of such a pebble system generally involves circulating a contiguous pebble mass through the entire series of pebble zones, including the interconnecting throats. That portion of the pebble mass descending through the heating chamber is heated to a suitable predetermined temperature above a desired conversion temperature in heat exchange relation with combustion, gas or other hot gases from any desired source. Pebbles are often heated in the heating chamber to temperatures as high as from 2,000 to 3,000 E, and in some cases higher, dependent upon the temperature requirements of the subsequent treating steps. The pebbles thus heated are contacted directly with one or more materials to be treated in one or more zones of the pebble heating system under suitable time and temperature conditions to effect the desired treatment. The pebble mass, having given upheat to the material or materials treated, descends through the bottom of the lowermost pebble zone, and is fed to an elevator for further handling, generally for transfer to an inlet at the top of the pebble heating chamber for reheating, and recirculation through the system.

In introducing an oil residuum feed into contact with a mass of pebbles, great difficulty is experienced in uniformly contacting all the pebbles in the mass, so that each pebble is coated with oil. Instead, disproportionately large amounts of oil reach only a relatively small part of the hot pebble mass, with the result that a considerable amount of the oil thus introduced moves as a free flowing liquid through a limited portion of the pebble mass, while the uncontacted portion of the pebble mass passes through the system unutilized. Considerable coking of the free-flowing oil to form carbonaceous byproducts takes place, thus reducing efficiency of the conversion to a level not economically feasible., Furthermore, agglomeration of pebbles and carbonaceous by-product thus formed takes place with the result that pebble circulation through the pebble system is impaired, and often stopped entirely. Agglomeration of carbonaceous matter and pebbles is, of course, undesirable, since the pebble system must then be shut down for an extended period for removal of the agglomerate and for readying the equipment for re-start-up.

My invention isconcerned with a combination process for converting normally gaseous hydrocarbon materials and normally liquid hydrocarbon materials, and with the utilization of a con tiguous mass of solid particulate heat transfer ma rials. movin through a plurality of contacting chambers, in carrying out such a process. My invention provides for an economic recovery of heat carried in the efllllentv from a normally gaseous hydrocarbon cracking zone, and, for utilization of that cracking efiluent in distributing a heavier hydrocarbon feed uniformly onto the surfaces Of solids particles in a. hydrocarbon conversion zone.

An Object .of. my invention is to provide for the conversion of hydrocarbons.

Another object is to provide a combination process for converting low-boiling normally gaseous hydrocarbon materials and higher boiling normally liquid hydrocarbon materials, and for the utilization of a pebble heater system in con ducting such a combination process.

It is another object to provide a combination thermal conversion process for the conversion of low-boiling hydrocarbons, such as methane, ethane, propane, and butanes, and higher boiling normally liquid hydrocarbon materials, such as gas oils, fuel oils, crude residuum, and the like.

It is another object to provide a process for cracking oil residuum stocks in a pebble heater system and for continuously removing carbon and carbon-rich materials from the system, formed therein as by-products of the cracking.

Another object is to provide a process for cracking an oil residuum in a pebble heater system, wherein oil is introduced into contact with pebbles in a manner that it uniformly coats the pebbles, and carbonaceous by-product of said conversion is continuously removed from the pebble system, on the pebble surfaces.

Another object is to provide for an efficient recovery of heat carried in a gaseous effluent from a hydrocarbon cracking chamber.

Other objects and advantages will be apparent to one skilled in the art from the accompanying discussion and disclosure.

In accordance with one embodiment of my invention, normally gaseous hydrocarbon materials and higher boiling normally liquid hydrocarbon materials are cracked in a pebble heater system comprising a pebble heating zone, a first cracking zone positioned below the pebble heating zone, and a second cracking zone positioned below the first cracking zone; a contiguous mass of pebbles is passed by gravity through the series of downwardly extending zones, thus filling the system with a contiguous moving mass of pebbles. Pebbles in the pebble heating zone are heated in any desired manner, preferably by introducing a combustible fuel-oxygen mixture into the heating zone and then burning it, and passing the resulting hot combustion gas upwardly through the pebbles to heat them to a temperature, above a cracking temperature required in the first cracking zone.

In the first cracking zone, that portion of the pebble mass previously heated in the pebble heating zone is contacted with a normally gaseous hydrocarbon, to heat that hydrocarbon to a cracking temperature, and to crack it. Pebbles in the first cracking zone lose heat to the cracking reaction and are concomitantly cooled to a temperature generally from 200 to 800 F. lower than their maximum initial temperature. Gaseous effluent from the first cracking zone, referred to hereafter as hot gaseous cracking product, is discharged at about the maximum cracking temperature therein, generally within the limits of 1300 and 2200 F. A hydrocarbon oil to be cracked, is introduced into the second cracking zone and passed concurrently therein with that portion of the pebble mass, previously utilized in the first cracking zone. The temperature of pebbles thus entering the second cracking zone is too low to provide heat at the necessary high temperature for cracking the oil contacted therewith, which oil-cracking tempera' tures are generally from about 800 to 1400 F., or in some cases higher. High temperature heat for cracking the oil in the second cracking zone is provided by passing hot gaseous cracking product, withdrawn from the first cracking zone, into the second cracking zone, in heat exchange and countercurrent flowv relation with oil andpebbles therein. The temperature of hot cracking product withdrawn from the first cracking zone. is from 200 to 800 F. higher, than the temperature of pebbles introduced into the second cracking zone, and the temperature of the resulting pebble-hot gaseous cracking product mixture therein is above the required temperature for cracking the oil. The oil in the second cracking zone is heated to its cracking temperature in heat exchange relation with the resulting hot pebblecracking product mixture, and cracked. Eifluent products from the pebble heater system are withdrawn from the second cracking zone and passed toa conventional product recovery system for separation and recovery of desired cracking product. Y I

Preferred low-boiling normally gaseous hydrocarbons which can be converted or cracked in' the process of my invention are parafiinic hydrocarbons having from 1 to 4 carbon atoms in the molecule, as methane, ethane, propane, and butanes. 'Ethane and/or propane can be respectively converted to ethylene and/or ethylene and propylene at high temperatures, low pressures, and short contact times. Methaneconversion to produce hydrogen under similar conditions of time, pressure, and higher temperature is readily accomplished. a

Total cracking efiluent, i. e., total cracking product, formed both in chambers 12 and I3 is withdrawn from chamber I 3 through effluent line 21 and passed to product separation means 28 comprising distillation equipment, solvent extraction equipment, storage, and the like, wellknown in the art for conducting a separation'and recovery of products from such a cracking efilu ent as withdrawn from chamber i3 through line 21, and not individually illustrated. From prod-. uct separation means 28 are withdrawn 2. light.

gas fraction comprising methane and hydrogen through line 29, low-boiling olefins such as ethylene, propylene, butylene, or mixtures thereof through line 30, low-boiling paraflins through line 31 including any unreacted feed to chamber I2, a light gas oil fraction through line 32, and a heavier gas oil fraction through line 33. Any small carbonaceous particles and any high-boiling by-product materials suspended in the gas-. eous eflluent in line 21 are separated in zone 28 and withdrawn through line 34. If desired, un-' reacted feed to chamber l2 canbe separated in zone 28 and withdrawn through line 36 instead of through line 3|, and recycled to line 23 for returnto cracking chamber l2. Similarly, if clesired, an oil cracking stock recovered in chamber 28 and withdrawn through either lines 32 or 33,

or both, can be recycled for further cracking to until oil thus introduced has finally contacted a suflicient portion of the pebble mass ID to uniformly coat the pebble surfaces. As provided by,

my process, agglomeration of the type discussed is prevented, for the reason that no large chunks or bodies of carbon are formed and accordingly,

the process is maintained over long operating pe.

fio'ds' as desiredwltheut interruption resulting from coking in chamber I3. I I I Upon initial contact of oil with pebbles in member I}, some of the lowest boiling components of the on may be immediately vaporized, in which case these vapor's are withdrawn along with cracking product thrdugh line 21; Heavier oil component's remaining on the hot pebble surfac'es'are conyerted as the pebble mass moves downwardly through chamber [3 as a function of the increased residence time in the pebble ma'ss'; As the pebble mass moves downwardly in chamber l3, the more refractory feed components remaining on the pebble surface are gradually converted to desired product as a function of the prolonged residence time. Finally, as pebblesapproach the pebble discharge point, i. e. discharge conduit H, the refractory carbonaceous by-Product remaining on the surfaces is substantially dry as a result of the reaction of substantially all reactive components on the pebbl e surfaces to form cracking product. Pebbles introduced into elevator I9 carry the dry carbonaceous matter from the conversion chamber, adhered to their surfaces, and are recycled to heating chamber H where they are reheated and burned free of the adhered carbonaceous matter, as discussed above, and then recirculated through the pebble system.

I find that when regulating the ratio of pebbles introduced into chamber 13 to oil feed introduced thereinto throughline 26, in a manner that the amount of oil introduced does not exceed the maximum amount that can be coked to dryness inchamber [3, no agglomeration takes place. Such a ratio is, of course, dependent upon the type of on feed utilized, as well as the characteristics of the specific pebble material utilized, such as pebble surface, specific heat, and the like. In general, however, I find that by regulating the weight ratio of pebbles to'oil feed introduced into chamber 13 to a value equal at least to 14:1, adequate pebble surface is available for absorbing the total oil introduced, and for preventing the occurrence of free flowing liquid through the pebble mass with the concomitant undesirable coking and agglomeration; Any higher weight ratio of pebbles to oil may be employed However, I find that when employing such a weight ratio exceeding about 30 l,,the heat from the cracked gases is not efficiently utilized. I

My process provides numerous advantages inadditionto those above discussed. Inthe first place, heat carried from the cracking chamber I2 in gaseous effluent through-line 24' is generally utilized invarious heat exchange steps, often in an inefficient manner. However, as provided by my invention, that heat is efficiently utilized to heat pebbles and oil in chamber l3, and thereby to crack the oil feed' to the desired cracking product. The hot gaseousproduct from chamber l2 is not only quenched, but reduces the partial reaction in chamber (3 is uniformly deposited onthe pebble surfaces and is continuously and completely carried from chamber t3 and introduced into heating chamber being further utilized as fuel, in chamber II, to provide the required" hot heat exchange gases therein. Or-

dinarily, carbonaceous formed cracking heavy oils is not further usable. In-

herently, with the utilization ofearbonacecus byproduct in this manner, pebbles are reconditioned, i. e. burned free of carbon, and reheated, for recirculation through" the pebble system to maintain the combination cracking process of my invention on a continuousbasis over an operating'period of any desired duration. N

My invention provides for increased yields oi oi l cracking productb'y virtue oI the uniform pebble-oil coating that takes place as above de scribed. The more refractory ureed compo nents can be reacted as a function of the prolonged residence time of the feed coated pebbles in the cracking chamber, so that the only carbonaceous by-product remaining is thedry byproduct, having a' high content of elemental carbon. I I I I 'I I I In conducting the process of my invention, 1 can crack ethane i n cracking chamber H at a pressure of from 5' to 40 p. s. i. a., a temperature of from 1300 to 2200 F., preferably 1500 to 1900 F., and for a contact time of from 0.001 to; 1 Second, preferably from 0.05 to 0.2 second. 11 propane, of propane and ethane are cracked in chamber [2, similar conditions can be employed; as for example, a pressure (if from 5 to 40 m0re preferably from 5 to 25p. s'. i. a., a temperature of from 1200 to 200051 more preferably from about 1400 to 1800 F., and a contact time of from 0.02 to 0.15 second, preferably 0.0? to 0.5

second. Similar, but somewhat milder conditions can be employed in chamber I when cracking butanes, as for example, a temperature within the limits of about 1000 to 1600 F., a preSsure of from 5 to 40 p. s. i. a"., and a contact time of from 0.01 to 0.10 second. I I I I In the conversion of the oil feed in cracking chamber I3, I prefer an operating pressure of from 5 to 40, preferably from 5 to 25 p. s. i. g., a temperature of from 950 to 1600" F., preferably 1100 to 1400 F., and a reaction time of from 0.2 to 3.5 seconds, preferably from 1 to 2 seconds. I

Although I have indicated product s'e'iparation means 28 diagrammatically, it is to be understood that zone 28 includes means for quenching the combinedeilluentsdischarged from chamber [3 through c'ond'uitZl' to a temperature of 900 F. or less, preferably toa lower temperature within thelimits of 525 to 725 F. II I I Advantages of this invention are illustrated in the'following example. The reactants and their proportions and their specific ingredients are presented as being typical and should not be construed to limit the invention unduly. The

example is presented with reference to the attached drawing. I I I Ethane is introduced into cracking chamber [2 and cracked at a rate of 70,000 standard cubic feet per" hour at a temperature of 1850 F. for a contacttilne of 0105 second. A 10 degree APL reduced crude preheated to atemp'erature of 900 F.' and introduced into chamber l3 at a point in an upper portion thereof at a rate of 680 barrels per" day. Pebbles are passed by, gravity through the oil cracking Cha mber IIl' in a weight ratio to reduced crude introduced there into of about 20':1. Total: gaseous efilulent is withdrawn from the ethane cracking chamber I2 and introduced into the oil cracking cham ber l3 at a point in; the lower portion thereof and passed countercurrent'ly therein with respect to oil and pebbles! The temperature of total gaseous e'filulentthus introduced into 9 chamber I3 is about 1800" F., and pebbles introduced thereinto are at a temperature of about 1000 F. Pebbles and oil are heated in heat exchange relation with hot gases from chamber l2 to a temperature of 1250 F. The reaction time is 1.5 seconds.

The ethane conversion in chamber I2 is maintained at a pressure slightly higher than that of the oil conversion in chamber Hi, the latter taking place at about 2 p. s. i. g. Pebbles discharged from the oil cracking chamber I3 are at a temperature of about 1000 F., dependent largely upon the location of the point of introduction of hot gases into chamber l3, i. e. the higher the point of introduction of hot gases the lower the temperature of the discharged pebbles. It is advantageous that thepoint of introduction be somewhat above the bottom end of the oil cracking chamber to permit additional residence time of the feed-coated pebbles in chamber 13 subsequent to initial contact thereof with hot gases. In this manner, extended time is provided for cracking any remaining highly refractory oil feed components.

The combined cracking effluents are withdrawn from the oil cracking chamber and quenched to a temperature of 705 F. in heat exchange relation with a refractory quench oil, or water.

Products resulting from the combination ethane and reduced crude cracking are summarized in the table herebelow. In the first column of the table are presented total production of cracking product in terms of pounds per day as obtained in accordance with the process of my invention; in the second column are preserlited total production when cracking ethane on y.

Production Total Profrom Ethane duction, Cracking pounds/day nly,

pounds/day 8, 500 8, 000 23, 100 14, 800 7, 600 7, 600 100, 900 79, 500 10,000 7, 800 12, 600 1, 500 l, 100 100 9, 000 4, 500 4, 900 400 800 100 Light Oils 1 68, 600 S, 700 Heavy Tar l 89,300 oke 34, 600

1 Relatively rich in aromatics.

My process is flexible in a considerable degree. I find that by decreasing the heavy oil feed rate, larger amounts of olefinic hydrocarbons and smaller amounts of liquid products are produced.

As will be evident to those skilled in the art, various modifications of this inventioncan be made, or followed, in the light of this disclosure and discussion, without departing from the spirit or scope of this disclosure or from the scope of the claims.

I claim:

1. A combination process for cracking normally gaseous hydrocarbon materials and higher boiling normally liquid hydrocarbon materials, comprising gravitationally passing a flowable contiguous mass of solid particulate material through a series of zones comprising a solids heating zone, a first cracking zone positioned below said solids heating zone, and a second crackiii ing zone positioned below said first cracking zone; introducing a combustible fuel mixture containing suiiicient oxygen for utilization described hereafter into said solids heating zone and therein burning said fuel; passing hot combustion gas formed by said burning in countercurrent fiow and heat exchange relation with that portion of said solids mass in said heating zone to heat same to a predetermined temperature above a cracking temperature to be utilized in said first cracking zone; introducing a normally gaseous hydrocarbon into said first cracking zone and therein heating same to said cracking temperature to form cracking product in countercurrent flow and heat exchange relation with a portion of said solids mass heated as above described; introducing a hydrocarbon oil in the liquid phase into said second cracking zone in concurrent flow relation therein with a portion of said solids mass previously utilized in said first cracking zone; the temperature of the solids entering said second cracking zone being too low to effect substantial cracking of said oil; withdrawing hot gaseous effluent from said first cracking zone and introducing same into said second cracking zone in countercurrent flow and heat exchange relation with said oil and said solids mass therein, whereby oil and solids in said second cracking zone are heated, and oil is uniformly distributed therein on the surfaces of said solids, and gaseous cracking product in said effluent is quenched; the temperature of the resulting solids-gaseous efiluent admixture in said second cracking zone being above that required for cracking said oil, whereby said oil on the solids surfaces is cracked and resulting carbonaceous by-product is uniformly deposited on said surfaces; withdrawing solids coated with said carbonaceous by-product from said second cracking zone, and passing same to said solids heating zone; in said solids heating zone burning said carbonaceous by-product with oxygen introduced with said combustible mixture as above described, whereby said carbonaceous by-product is efiiciently utilized as fuel to produce hot heat exchange gas in said heating zone and solids are reconditioned for recirculation through said zones, and recovering efiluents of cracking from said second cracking zone.

2. A combination process for cracking a normally gaseous hydrocarbon and a higher boiling normally liquid hydrocarbon, comprising passing a contiguous mass of pebbles through a series of zones comprising a pebble heating zone, a first cracking zone positioned below said peb-f ble heating zone, and a second cracking zone positioned belowsaid first cracking zone; passing a hot gas in countercurrent flow and heat exchange relation with that portionof said pebble mass in said heating zone to heat same to a temperature above that required for cracking a normally gaseous hydrocarbon; introducing a normally gaseous hydrocarbon into said first cracking zone and therein cracking same in countercurrent flow and heat exchange relation with pebbles heated as described above; introducing a hydrocarbon oil in the liquid phase into concurrent flow relation with pebbles in said second cracking zone; the temperature of'the pebbles entering said second cracking zone being too low to effect substantial cracking of said oil; withdrawing hot gaseous effluent from said first cracking zone and introducing same into said second cracking zone in countercurrent flow and heat exchange relation with said oil and pebbles therein; the temperature of the resulting pebbles-gaseous mixture in said second cracking zone being above that required for cracking said oil, whereby said oil is cracked; withdrawing pebbles from said second cracking zone; and recovering gaseous effluents of cracking from said second cracking zone.

3- The process of claim 2 wherein said oil is a petroleum residuum having a boiling range above 700 F.

4. The process of claim 2 wherein said oil is a gas oil.

5. The process of claim 2 wherein said normally gaseous hydrocarbon contains from 2 to 3 carbon atoms in the molecule.

6. The process of claim 2 wherein said oil is preheated prior to introduction of same into said second cracking zone.

'7. A combination process for cracking a normally gaseous hydrocarbon and a hydrocarbon oil, comprising gravitationally passing a contiguous mass of pebbles through a series of zones comprising a pebble heating zone, a first cracking zone and a second cracking zone; introducing a combustible fuel mixture capable of burning to produce combustion gas at a temperature within the limits of 1400 to 3000 F. and containing suflicient oxygen for utilization described hereafter into said solids heating zone and therein burning said fuel; passing hot combustion gas formed by said burning in countercurrent heat exchange relation with that portion of said pebble mass in said heating zone to heat said mass therein to a temperature of from 100 to 300 F. above a cracking temperature within the limits of 1300 to 2200 F. to be utilized in said first cracking zone; introducing a normally gaseous hydrocarbon into said first cracking zone and therein cracking same in countercurrent flow and heat exchange relation with a portion of said pebble mass previously heated in said heating zone as described above; pebbles in said first cracking zone giving up heat to said cracking and being passed from said first cracking zone to said second cracking zone at the incipient cracking temperature of said oil; introducing a hydrocarbon oil in the liquid phase into said second cracking zone in concurrent fiow relation therein with pebbles from said first cracking zone; with drawing hot gaseous effluent from said first cracking zoneat the maximum gas temperature therein; introducing said hot gaseous effluent into said second cracking zone in countercurrent flow and heat exchange relation with said oil and said pebbles therein to uniformly distribute liquid oil on said pebbles and to heat said oil and crack same at a temperature within the limits of 800 to 1600 F.; carbonaceous by-product from oil cracking in said second cracking zone being formed as a uniform coating on pebble surfaces therein; withdrawing pebbles from said secondcracking zone containing adhered carbonaceous by-product of oil cracking, and passing same to said pebble heating zone; burning said carbonaceous by-product in said heating zone with oxygen introduced with said combustible mixture as above described; and recovering gaseous effluents from saidsecond cracking zone.

8. A combination process for cracking a normally gaseous hydrocarbon and a hydrocarbon oil, comprising cracking a normally gaseous hydrocarbon in countercurrent flow and heat exchange relation with hot pebbles in a first crack ing zone, introducing a hydrocarbon oil in the liquid phase and pebbles from said first cracking zone in concurrent flow relation into a second cracking zone, said pebbles entering said second cracking zone at a temperature too low to effect substantial cracking of said oil, withdrawing hot gaseous effluent from said first cracking zone and introducing same into countercurrent fiow relation with liquid oil and pebbles in said second cracking zone to heat said oil and crack same, and recovering product of cracking from said second cracking zone.

9. A combination process for cracking ethane and a petroleum residuum stock, comprising passing a contiguous mass of pebbles through a series of zones comprising a pebble heating zone. a first. cracking zone positioned below said pebble heating zone, and a second cracking zone positioned below said first cracking zone; passing a hot gas in countercurrent flow and heat exchange relation with that portion of said pebble mass in said heating zone to heat same to a temperature from to 300 F. above a cracking temperature to be employed in said first cracking zone and selected from within the limits of from 1300 to 2200 F.; introducing ethane into said first cracking zone and cracking same therein in countercurrent flow and heat exchange relation with pebbles heated in said heating zone as described; preheating a hydrocarbon residuum oil having a boiling range above 850 F; to a temperature within the limits of 800 to 1400 F; and introducing the preheated oil in the liquid phase into concurrent flow relation with pebbles in said second zone; said pebbles entering said second zone at the incipient cracking temperature of said oil; maintaining a ratio of pebbles to oil introduced into said second zone within the limits of 14:1 to 30:1; withdrawing hot gaseous effluent from said first cracking zone and introducing same into said second cracking zone in countercurrent flow and heat exchange relation with said oil and pebbles therein; the temperature of the resulting pebbles-gaseous effluent mixture in said second cracking zone being above that required to crack said oil at a temperature within the limits of 800 to 1400 R, whereby said oil is cracked; withdrawing pebbles from said second zone containing carbonaceous by-product of oil cracking on their surfaces and returning pebbles thus withdrawn to said pebble heating zone; in said heating zone burning said carbonaceous by-product free from said pebblesurfaces; and recovering olefins and aromatic hydrocarbons from effiuent of said second cracking zone as products of the process.

MYRON O. KILPATRICK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,016,651 Pennrich Oct. 8, 1935 2,082,636 Keith June 1, 1937 2,326,553 Munday Aug. 10, 1943 2,439,730 Happel Apr. 13, 1948 2,448,257 Evans Aug. 31, 1948 

1. A COMBINATION PROCESS FOR CRACKING NORMALLY GASEOUS HYDROCARBON MATERIALS AND HIGHER BOILING NORMALLY LIQUID HYDROCARBON MATERIALS, COMPRISING GRAVITATIONALLY PASSING A FLOWABLE CONTIGUOUS MASS OF SOLID PARTICULATE MATERIAL THROUGH MASS OF SOLID PARTICULATE MATERIAL HEATING ZONE, A FIRST CRACKING ZONE POSITIONED BELOW SAID SOLIDS HEATING ZONE, AND A SECOND CRACKING ZONE POSITIONED BELOW SAID FIRST CRACKING ZONE; INTRODUCING A COMBUSTIBLE FUEL MIXTURE CONTAINING SUFFICIENT OXYGEN FOR UTILIZATION DESCRIBED HEREAFTER INTO SAID SOLIDS HEATING ZONE AND THEREIN BURINING SAID FUEL; PASSING HOT COMBUSTION GAS FORMED BY SAID BURNING IN COUNTERCURRENT FLOW AND HEAT EXCHANGE RELATION WITH THAT PORTIN OF SAID SOLIDS MASS IN SAID HEATING ZONE TO HEAT SAME TO A PREDETERMINED TEMPERAURE ABOVE A CRACKING TEMPERATURE TO BE UTILIZED IN SAID FIRST CRACKING ZONE; INTRODUCING A NORMALLY GASEOUS HYDROCARBON INTO SAID FIRST CRACKING ZONE AND THEREIN HEATING SAME TO SAID CRACKING TEMPERATURE TO FORM CRACKING PRODUCT IN COUNTERCURRENT FLOW AND HEAT EXCHANGE RELATION WITH A PORTION OF SAID SOLIDS MASS HEATED AS ABOVE DESCRIBED; INTRODUCING A HYDROCARBON OIL IN THE LIQUID PHASE INTO SAID SECOND CRACKING ZONE IN CONCURRENT FLOW RELATION THEREIN WITH A PORTION OF SAID SOLIDS MASS PREVIOUSLY UTILIZED IN SAID FIRST CRACKING ZONE; THE TEMPERATURE OF THE SOLIDS ENTERING SAID SECOND CRACKING ZONE BEING TOO LOW TO EFFECT SUBSTANTIAL CRACKING OF SAID OIL; WITHDRAWING HOT GASEOUS EFFLUENT FROM SAID FIRST CRACKING ZONE AND INTRODUCING SAME INTO SAID SECOND CRACKING ZONE IN COUNTERCURRENT FLOW AND HEAT EXCHANGE RELATION WITH SAID OIL AND SAID SOLIDS MASS THEREIN, WHEREBY OIL AND SOLIDS IN SAID SECOND CRACKING ZONE AND HEATED, AND OIL IS UNIFORMLY DISTRIBUTED THEREIN ON THE SURFACES OF SAID SOLIDS, AND GASEOUS CRACKING PRODUCT IN SAID EFFLUENT IS QUENCHED; THE TEMPERATURE OF THE RESULTING SOLIDS-GASEOUS EFFLUENT ADMISTURE IN SAID SECOND CRACKING ZONE BEING ABOVE THAT REQUIRED FOR CRACKING SAID OIL, WHEREBY SAD OIL ON THE SOLIDS SURFACES IS CRACKED AND RESULTING CARBONACEOUS BY-PRODUCT IS UNFORMLY DEPOSITED ON SAID CRACKING ZONE, AND PASSING SAME TO SAID SAID CARBONACEOUS BY-PRODUCT FROM SAID SECON CRACKING ZONE, AND PASSING SAME TO SAID SOLIDS HEATING ZONE; IN SAID SOLIDS HEATING ZONE BURNING SAID CARBONACDOUS BY-PRODUCT WITH OXYGEN INTRODUCED WITH SAID COMBUSTIBLE MIXTURE AS ABOVE DESCRIBED, WHEREBY SAID CARBONACEOUS BY-PRODUCT IS EFFICIENTLY UTILIZED AS FUEL TO PRODUCE HOT HEAT EXCHANGE GAS IN SAID HEATING ZONE AND SOLIDS ARE RECONDITIONED FR RECIRCULATION THROUGH SAID ZONES, AND RECOVERING EFFLUENTS OF CRACKING FROM SAID SECOND CRACKING ZONE. 